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  #61  
Old 03-23-2016, 12:02 PM
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smokyray smokyray is offline
 
Join Date: Jan 2005
Location: TX32
Posts: 1,891
Default Light is right...

Quote:
Originally Posted by rockit View Post
I am look at purchasing a RV-7 and it has a fixed pitch prop. I have low tail wheel time in a champ but lots of time in a RV-9A. Someone mentioned a CS prop is better because it will help you slow down the airplane and better for low TW time pilots.
I was wondering if anyone has an opinion on this.
Thanks.
Ravi,
Age old question. F16 Fighter weapons school answer? It depends.
Long ago in a galaxy not so far away I built a light, simple RV4 that weighed in at 925lbs and cost me $21K in 1994 dollars. This was before pre-drilled, pre-punched, pre-fab RV's, the internet or chat groups and social media or even this wonderful site "DR" built. Back then RV builders (RV3,4) bragging rights weren't the HP of the engine or amount of glass in the panel but the empty weight, total cost and efficiency! Also a prime topic for discussion was utilizing clean up mods, the coolest personal innovations and of course Propellers as most folks used wood, FP props.

I began flying my 4 with a wood Sterba FP prop and 0-320 and found the RV4 to be an easy tail-dragger compared to our family Taylorcraft. I also found adjusting to a FP wood prop on a clean airplane wasn't difficult at all, just required practice. Later I would install and test a one-off Craig Catto masterpiece prototype prop that would become the RV standard. Much improvement and performance.
Useful tips:
1. Reduce engine idle to 600RPM. (why? less rpm equals less thrust in pattern)
2. Pre-planning. Slowing down earlier, planning descents or using overhead traffic patterns with no traffic to bleed off energy.
3. Practicing both straight in flame out (engine failure) and standard traffic patterns at best glide speed (85 KIAS/100mph)
4. Challenge yourself to fly final approach at 65KIAS/70MPH with flaps. (I use 60KIAS)

Constant Speed RV's are nice for their own reasons not to mention flexibility, a bit shorter takeoffs and the air brake option you mention. Their drawbacks though (cost,weight,maintenance,engine failure glide distance, etc) don't add up for a Jurassic builder/flyer like myself.

The lighter they are, the better they fly...
V/R
Smokey

Last edited by smokyray : 03-23-2016 at 12:10 PM.
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  #62  
Old 04-10-2016, 06:04 PM
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maniago maniago is offline
 
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Location: Bowie MD
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I've read a fair amount of work being done to improve on FP prop designs (Catto and other) over the years but had any of this flowed to the CS airfoils? Hartznell has their blended, which has a tough to swallow premium, but does it represent a similar leap in performance for CS type props? Whirlwind props are even more expensive, but any better tech? IDK.

Seems like we should have already seen more improvement to CS airfoils than is apparent, at least to me.
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Busby MustangII (FoldingWing) Pending DAR.
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  #63  
Old 04-10-2016, 06:58 PM
rockwoodrv9 rockwoodrv9 is offline
 
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Location: Meridian ID, Aspen CO, Okemos MI
Posts: 2,645
Default Speed Brake?

Not to go too far off this thread, but the big issue I see between CS and Fixed is slowing down. Especially with the 9. I just read an article in Kitplanes about the CX5 Thatcher and it has a speed brake that drops down between the gear legs. Maybe that is the answer.
http://www.kitplanes.com/issues/33_4...5_21502-1.html

I am a low time pilot and the thought of one more thing to worry about with a CS prop helped my decision to go with a Catto. All the planes I am taking lessons in have a Fixed prop too. I did put the recess in my firewall and my engine can be converted. Maybe some day I will change. It has been an interesting discussion and learning experience.
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  #64  
Old 04-10-2016, 07:08 PM
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maniago maniago is offline
 
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One thing my CFI reminded me with the FP planes was you can always trade airspeed for alt to slow down. Of course not in the pattern, but way before - which brings us back to planning. After all you can slow down a lot on a 5mi approach to the down wind.

Remember that mooneys all have CS props. But they still need to plan their arrivals not to be speeding around the pattern etc. Some even have speed brakes, and so the same arguments about props and planning being made here (ie slowing) revolve over at their sites about speed brakes and planning.....
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Busby MustangII (FoldingWing) Pending DAR.
Don't be a hater; I'm a cousin with thin wings!
N251Y (res)
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  #65  
Old 04-11-2016, 06:53 AM
brad walton brad walton is offline
 
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It's simply a case of energy management.
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  #66  
Old 04-11-2016, 01:36 PM
Jimzim Jimzim is offline
 
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Location: Arvada, CO
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So a friend and I both built RV7's with o-360's. He went with CS, I opted for FP. We were chatting recently, when I made a comment about kind of wishing I had gone with a constant speed. He replied that he was thinking he should have went FP. Go figure!
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  #67  
Old 04-12-2016, 05:06 PM
meloosifah meloosifah is offline
 
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The decider for me was that in all the FP/CS debate I have yet to see one documented instance of someone voluntarily trading CS for FP. I am certain my -8 will outperform my cub, even with a 2x4 on the nose, but I got a deal on a CS and the overall VAF response makes me believe that if you can do CS you should. If I ever build a -3 it will have a Catto for weight purposes only. On an -8 I can save the difference elsewhere.
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  #68  
Old 04-12-2016, 05:48 PM
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plehrke plehrke is offline
 
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Quote:
Originally Posted by meloosifah View Post
The decider for me was that in all the FP/CS debate I have yet to see one documented instance of someone voluntarily trading CS for FP.
To really pull all the debates into one big ball, I have never heard any one with glass voluntarily trade it in for steam. Nor have I heard of some one that primed decide they wanted to un-prime. Sunk cost.
The debate is not if primed constant speed glass is better, the point is if unprimed fixed pitch steam is good enough for me the builder or buyer. That is an individual decision and one of the big perks of Experimental Amateur Built.
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  #69  
Old 04-12-2016, 06:00 PM
YellowJacket RV9 YellowJacket RV9 is offline
 
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Location: Clearwater, FL KCLW
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Quote:
Originally Posted by plehrke View Post
To really pull all the debates into one big ball, I have never heard any one with glass voluntarily trade it in for steam. Nor have I heard of some one that primed decide they wanted to un-prime. Sunk cost.
The debate is not if primed constant speed glass is better, the point is if unprimed fixed pitch steam is good enough for me the builder or buyer. That is an individual decision and one of the big perks of Experimental Amateur Built.
Vlad is FP, steam, (not sure about primed), and I'm pretty sure he has more fun than any of us...

Chris
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  #70  
Old 04-12-2016, 06:35 PM
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N941WR N941WR is offline
 
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Quote:
Originally Posted by rockwoodrv9 View Post
Not to go too far off this thread, but the big issue I see between CS and Fixed is slowing down. Especially with the 9. I just read an article in Kitplanes about the CX5 Thatcher and it has a speed brake that drops down between the gear legs. Maybe that is the answer.
http://www.kitplanes.com/issues/33_4...5_21502-1.html

I am a low time pilot and the thought of one more thing to worry about with a CS prop helped my decision to go with a Catto. All the planes I am taking lessons in have a Fixed prop too. I did put the recess in my firewall and my engine can be converted. Maybe some day I will change. It has been an interesting discussion and learning experience.
Not to worry. I went from a 65 T-Craft to my FP -9 and didn't have any issues. The only time slowing down is an issue is when flying formation with a CS prop and he pulls all the power off at once.

Other than that, don't come ripping into the pattern, running over Cubs and such at 150+ knots, and pull the power expecting to slow down to flap speed. It won't happen.

Plan on being at pattern altitude three miles before the airport and slowing. By the time you are ready to put out the flaps you should be at the correct speed. On final, speed is critical, do not let it speed up, even 5 knots!
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RV-9 (Yes, it's a dragon tail)
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